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June 15, 2008 6:53 PM   Subscribe

Converting to a drought-friendly lawn, should we use chemicals or not?

In Los Angeles, converting front and back lawns to drought-friendly landscaping after letting the grass die all winter/spring.

One gardener wants to use RoundUp as part of the prep, but the other (somewhat cheaper) advised it was not necessary, and finally agreed to do RoundUp "where necessary" (their words.)

So we were set to go with the cheaper gardener, when a minor accident with the sprinkler system let the ground get watered for four days in the amount we used to water it. Two weeks later the front lawn (full sun) is still dead, but the back lawn (much shade) has sprung to vibrant life.

Looking for advice as to whether RoundUp is necessary or not, ideally based on personal experience in Southern California (San Fernando Valley), and also whether you've experienced any issues with animals or kids interacting badly with RoundUp after re-planting is completed (they'll have no access while everything's torn up.)

posted by davejay to Home & Garden (12 answers total) 1 user marked this as a favorite
Best answer: Although I always try to reach for a non-chemical solution (no pun intended) first, I would go with the RoundUp in this instance because of what you're trying to accomplish: a complete, total kill. If you do not use a RoundUp/glycophosphate spray, you will continue to have problems of resprouting. IANACE (I am not a chemical engineer), but my experience (Midwest acreage) with RoundUp is that you spray it, make sure there is no access while wet (1 hour or so) and then there's no problem re. kids/dogs/cats/spouses. Use only what you need, following the label's dilution formulas and you'll have no problems. Make sure they spray early in the day (but after the dew is off) so it has all day in full sun to dry, fix, and begin to work.

Of course, you have to make sure you don't do what my brother-in-law did: forget to empty the sprayer immediately, and then a few weeks later puts a selective, broad-leaf only herbicide in with the remains of the roundup and proceed to spray about 2 acres of newly seeded turf grass. Not to mention he did this about a month before his son's H.S. graduation party. That's a fun family story we get to repeat every year around the Thanksgiving table.
posted by webhund at 8:48 PM on June 15, 2008

If you're going to tear everything up I wouldn't bother. Once you stop watering it any grass left over isn't going to survive the rest of the summer.
posted by fshgrl at 8:53 PM on June 15, 2008

Best answer: If you're converting your existing lawn space to something that needs less water, you will presumably end up giving it less water than it currently needs, and your new drought-tolerant plants should handily outcompete the remains of the existing grass.

That said, a one-time application of glyphosate to kill off the back lawn is unlikely to cause you any major problems. Do it the way webhund said. Glyphosate's half-life in soil is about two weeks, but you don't want it getting into your waterways.

Once all the old plants have died off and dried, top-dressing with a decent compost should easily compensate for any damage the glyphosate has done to your soil's microflora.
posted by flabdablet at 10:08 PM on June 15, 2008

Best answer: After decades of use Round-Up's active ingredient has such a low risk potential that there are no occupational exposure limits established. Glyphosate is extreemly short lived in the environment. If your former lawn is dead spraying any amount of Round-Up is a waste of time and effort, it has almost no value as a pre-emergent. It only works when it is sprayed onto and absorbed by living plants where is is translocated into the roots.

You may have a problem where the lawn was with seeds from the grass and from weed seeds that have blown or been carried in. When you start watering those seeds will germinate and some will continue to germinate for years. A good deep layer of mulch is great for keeping unwanted seeds from germinating. You can supplement the mulch with a pre-emergent like Preen organic or Amaze. Might want to consider weed barrier fabric too. See your local OSH, Home Depot or other garden supply store.

Here in southern SLO county we're near the end of a cul de sac where grass covered front yards are the norm and the gardeners come in once a week to mow, blow and go. We've got a front yard full of drought tolerant plants, mostly California natives. I use the combination above; bark mulch, Preen and patches of weed barrier fabric here and there. Our California poppies are about done now, their seeds will be in the soil for next year. We have something blooming almost year around, and we have lots of bees, butterflys and birds.

Good luck and enjoy yours.
posted by X4ster at 11:04 PM on June 15, 2008

Just don't water it until the proper planting time for California lawns: autumn. You're going to use a lot of water establishing a new lawn, "drought friendly" or not, if you plant in the summer. I would wait till the first rains, let what ever weed seeds sprout with the first rain, remove those, and then put down your grass seed.
posted by oneirodynia at 9:16 AM on June 16, 2008

Best answer: The same goes with "drought" friendly plants as well- any planting now is going to use more water than any established garden. I know the industty doesn't work this way, but planting in dry-summer climates is best done when the weather is cooler, and hopefully, rainier. You use less water, the plants are less stressed, and can establish a good , deep root system over winter, which will help with drought tolerance in summer.
posted by oneirodynia at 9:20 AM on June 16, 2008

I did some checking on RoundUp since we take our dogs outside in the back yard, where I was planning to use it. The most specific information I found was that for RoundUp to harm an animal, you'd pretty well have to pour it down their throats. It shouldn't present a danger. (Now if the damn stuff would just work on desert-adapted weeds. Little bastards are tough.)
posted by azpenguin at 10:31 AM on June 16, 2008

Response by poster: Wow, this thread had a very strong signal-to-noise ratio; thanks for all of your input.

The new plan: RoundUp in the back and front for sure, and the new top layer as suggested, but we won't plant anything new or turn on the water until things cool off late in the year -- we'll concentrate on laying down packed-dirt, gravel and/or stone in the appropriate places in the meantime.
posted by davejay at 6:12 PM on June 16, 2008

Note that anything you put on your lawn is a "chemical", because water is a chemical, oxygen is a chemical, and compost is full of chemicals - they just happen to be good chemicals.
posted by betterton at 8:06 PM on June 16, 2008

RoundUp in the back and front for sure, and the new top layer as suggested, but we won't plant anything new or turn on the water until things cool off late in the year

I think you'd be better off delaying the RoundUp treatment until about three weeks before you do intend to plant stuff. A living carpet of grass - even one that's gone dry and dormant - will keep the soil underneath in better condition than a dead one.
posted by flabdablet at 11:38 PM on June 16, 2008

Oh, yeah - Roundup works best on active plants, because it relies on their inner transport mechanisms to get into their roots. So let your lawns do what they do until a month before you're ready to rip, then lull them into a false sense of security by watering them for a week (if they need it), then wait for a day when it's not going to be raining, and RoundUp them in the morning after the dew is off.
posted by flabdablet at 11:43 PM on June 16, 2008

Response by poster: Thanks again -- the new plan is that we're waiting until fall, since we got hit with epic hot days (106F) last week.
posted by davejay at 6:22 PM on June 24, 2008

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